The present invention relates in general to laser treatment of dermatological imperfections. The invention relates in particular to non-ablative laser treatment for reducing wrinkles.
Effective aesthetic treatment of wrinkles has hitherto involved primarily the removal of tissue and subsequent wound healing to improve their appearance. Chemical peels, dermabrasion, and ablative laser skin resurfacing are used routinely for this purpose. However, all of these methods leave open wounds which must subsequently heal. There is need for a laser treatment method for reducing wrinkles which does not leave such open wounds.
The present invention is directed to a method for treating wrinkles. In one aspect, the method of the present invention comprises irradiating the skin to be treated with light (electromagnetic radiation) having a wavelength selected such that it is preferentially absorbed in a dermal region of the skin including a melanocyte layer of the epidermis and a region of superficial vasculature immediately below the melanocyte layer. The light is delivered at a fluence sufficient that the preferential absorption thereof stimulates a wound healing (regenerative) response in the dermal region without causing a wound. The wound healing response promotes growth of dermal extracellular matrix (ECM) in the upper dermal region. The growth of dermal ECM reduces the depth of the wrinkles.
Preferably, the light has a wavelength between about 525 and 550 nanometers (nm). The light may be delivered in the form of pulses thereof or as a continuous beam swept or scanned over an area of skin being treated.
In experimental treatments in accordance with the present invention, pulsed electromagnetic radiation having a wavelength of 532 nm, delivered by a frequency-doubled Nd:YAG laser was arranged to deliver a spot having a diameter of about 3 millimeters (mm). The pulse duration was about 2.0 milliseconds (ms). An average fluence of 5.5 Joules per square centimeter (J/cm2) was used in repeated treatments to treat eleven volunteer patients having facial wrinkles. There was on average a 52% improvement in the appearance of the wrinkles, as judged by the patients themselves.